**4. NPs delivery of cancer vaccines**

Cancer immunotherapy by vaccines depends on eliciting in patient the antitumor adaptive cellular immunity, which is, however, governed by potent Ag-presenting DCs able to activate CD8+ T cells and engender the Ag-specific CTLs. For this purpose, various immunotherapy strategies have been developed, including, in particular, using NP-based VADSs that are so elaborately designed as to promote APC cross-presentation of Ags and to deliver Ags and/or adjuvants targeting APCs, tissues, or organs such as dLNs, wherein APCs aggregate in large number ready for uptake of foreign substances, as can hardly be accomplished by soluble Ags or adjuvants alone [12].
